Science Siftings

New Zealand Tablet, 9 June 1910, Page 915

Science Siftings

BY 'VOLT'

Birth of the Tinplate. Tinplate making was introduced into England from Saxony in 1665, and the first tinplate factory in France was established in 1714. Tinplates were first made on a commercial basis in the United States at Pittsburg in 1872. A New Method of Electroplating.; A new method of electroplating which dispenses with plating bath and all expensive sources of electricity has been developed by A. Rosenberg, a chemist in England. Magnesium finely powdered is mixed with a salt of the plating metal or with the powdered metal itself, and ammonium sulphate. The mixture moistened with water is then spread over surface to plated. The magnesium, strongly electropositive, reacting with the moist electrolyte, goes into solution, while the metal is deposited. The Underground Ocean. Recent investigations by officers of the geological survey have brought to light facts about the enormous quantity of underground water contained in the crust of the globe which are calculated to astonish the lay mind. Below a depth of six miles it is believed that no water can exist in the rocks, because the tremendous pressure probably closes all pores; but above that level the quantity of underground water is estimated to be equal to one-third of all the water contained in the oceans. If poured over the land surface of the globe the underground water would, it is averred, be sufficient to cover it to a uniform depth of from 3000 ft to 3500 ft. Sound from Electric Lamp. Experiments in electricity by students of the Texas University engineering department have resulted in the production of articulate sound from a common arc lamp the feeding wire of which is connected with a telephone. Dr A. 0. Scott has interested himself in the experiment and says the result is due to the fact that the vibrations in the carbon of the lamp correspond exactly to those of an ordinary telephone receiver. The ; talking lamp is located in a room some distance from the 'phone in the engineering building, and students standing directly under it are able to hear conversations over the 'phone with perfect distinctiveness. Noises or conversations in the 'phone room cannot be heard at that distance .when communication with the 'phone is cut off. Monorail. :\. .. " v Civil engineers are not of one' mind regarding the value of Brennan s monorail. One writer in the London Times points out that while ordinary tramway rails weigh 1301 b a yard that is 2601 b a yard for the two, the monorail will probably have to be at least 3001 b a yard. Moreover as the whole weight is concentrated on that rail, the ties and roadbed will have to be heavier than when the weight is distributed over two rails. He adds that the strain on the roadbed is greater as the speed increases, and dwells on the difficulty the Germans had to keep it in order during the experiments of a few years ago with electric motors, when a speed of 120 miles an hour was attained. Finally, he says that as yet the.monorail car has hardly reached a speed of 60 miles an hour, and that were he to design a road for speeds from. 150 to 200 miles an hour, he would be more inclined to use three rails, or even four. The Sahara. ■• It is surprising to find throughout the Sahara grass lands tenanted with animal life, but more remarkable to know that it was formerly populous. Gautier found, absolute proof that long before the present age of rainfall, in what is known as the Neolithic or later Stone Age, a very large population inhabited part of the Sahara. He found their graves scattered over the grassy plain ; he found many hundreds of their drawings on the rocks, where they had pictured animal forms and other objects; he discovered the flattened stones which they had used for grinding grain. Ihese mill-stones show that agriculture was then developed in that region, and the grinding of grain into flour indicates considerable advance of civilisation. Here and there were many arrow-points, axes of polished stone, and other implements. It was many hundreds of yeavs ago that human beings inhabited this region, but as time is reckoned in geological epochs, thousands of farmers were tilling this part of the Sahara at a comparatively recent period. They were finally _ driven back into the Sudan by the increasing drought, and the world forgot that this region had ever been inhabited by man.